AHR researchers applied a potassium nitrate solution as a drench to seedlings of cos (cv. Quintas) and iceberg (cv. Toscanas) lettuce just before they were transplanted into the field at a commercial lettuce farm in Sydney.

Plants were assessed at four and seven weeks (commercial maturity) after transplanting and head fresh weights were recorded.

What we found

Potassium nitrate drenching resulted in larger plants four weeks after transplanting. The potassium nitrate treatment resulted in a 25% increase in shoot fresh weight compared to the control when applied to iceberg lettuce (cv. Toscanas) and a 22% increase in fresh weight in cos lettuce (cv. Quintus), four weeks after transplanting—both statistically significant.

At the harvest stage, the head weights of drenched iceberg lettuce plants were 19% higher, and cos lettuce 12% higher than the control plants. Again, both statistically significant.

Where to next

The researchers plan to expand their study to other treatments, such as controlling lettuce pests like lettuce aphids.

Resources

A fact sheet on controlling transplant shock in lettuce is available here